Turbine condenser for a steam turbine

ABSTRACT

A turbine condenser includes an area with condenser tubes for liquefying waste steam from the steam turbine, a chamber formed by condenser walls for receiving the waste steam, and a diverted steam channelling system for channelling diverted steam into the chamber in the turbine condenser, wherein the diverted steam channelling system includes an annular nozzle extending into the turbine condenser, the outlet end of which has an uneven edge.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2014/065349 filed Jul. 17, 2014, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP13178234 filed Jul. 26, 2013. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a turbine condenser for a steam turbine.

BACKGROUND OF INVENTION

Turbine condensers serve for the liquefaction of the exhaust steam of steam turbines. In the case of installations with combined gas and steam turbines, to be able to cover peak loads in energy demand, such installations are nowadays operated for most of the time only at gas turbine minimum load. If required, the gas turbine can then be accelerated very rapidly.

The waste heat generated by the gas turbine at minimum load must however continue to be dissipated, which is realized by way of the heat recovery steam generator connected downstream of the gas turbine. Since the steam generated in the heat recovery steam generator however cannot be converted into electricity by way of the downstream steam turbine and the generator, said excess produced steam is conducted, bypassing the steam turbine via bypass-steam introduction lines, directly into the turbine condenser.

Such bypass-steam introduction lines are in this case normally equipped with a bypass valve for regulating the bypass-steam flow rate, a perforated cage as a throttle device for expansion of the bypass steam, and a water injection means for cooling of the bypass steam. The heat gradient that must be throttled in a bypass-steam introduction line of said type is however generally very great. The steam pressure upstream of the bypass valve is normally up to 45 bar, whereas the counterpressure in the turbine condenser can be stated as being approximately 0.1 bar. If said bypass-steam flow now passes, at a high pressure level, from the bypass-steam device into the turbine condenser at a considerably lower steam pressure level, this gives rise to high speed gradients in the edge regions of the inflowing bypass steam. The abrupt expansion then has the result that, depending on the pressure gradient, a hypersonic flow field is locally generated. Furthermore, there is the risk of impinged-on components, such as for example the adjacent turbine blades, the condenser tubes or the condenser walls, also being caused to vibrate. Both have the effect that, during the operation of the installation, sound emissions are increased, and thus prescribed maximum values are possibly exceeded.

SUMMARY OF INVENTION

It is an object of the invention to provide a turbine condenser which permits reduced sound emissions.

Said object is achieved by means of the turbine generator having the features of the independent claim.

By virtue of the fact that, in the region in which the steam from the bypass-steam introduction device enters the turbine condenser, there is provided a ring-shaped nozzle with a non-uniform edge at the outlet end, improved mixing occurs over the cross section of the bypass-steam flow that enters, giving rise to less intense speed gradients in the edge regions of the bypass steam flowing into the turbine condenser. The high speed gradients that normally prevail specifically in the edge region of the inflowing bypass steam, which high speed gradients can lead to intense turbulence upon entry into the turbine condenser owing to the associated high pressure gradient, are thus lessened by the non-uniform edge. Elevations and/or indentations formed at regular or irregular intervals over the edge situated at the outflowing end of the bypass-steam introduction device have the effect that the bypass steam is locally changed already at the outlet, and is thus better mixed over its cross section. This results in a lessening of the speed gradients, and thus in less intense turbulence. Since said turbulence makes a substantial contribution to the sound emissions, it is thus possible, as a result of the improved mixing and the associated lessening of the speed gradients in the edge regions of the inflowing bypass steam, for the sound emissions to be reduced in an effective manner.

The edge region of the nozzle is advantageously in the form of a chevron nozzle with a serrated or toothed outlet edge. This yields particularly effective mixing over the entire cross section of the inflowing bypass steam; the resulting lessening of the uniform speed gradients thus leads to a particularly effective reduction of the sound emissions.

Further advantageous refinements of the invention will emerge from the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be discussed by way of an example below on the basis of a FIGURE.

The sole FIGURE schematically shows a region of the turbine condenser in accordance with aspects of the invention.

DETAILED DESCRIPTION OF INVENTION

Said FIGURE schematically shows the region of the turbine condenser in which the bypass steam D is introduced from the bypass-steam introduction device 1 into the turbine condenser 2. By means of a so-called sparger tube 3—or very generally a perforated cage—as a throttle device, the bypass steam D is introduced into the turbine condenser. At the outlet of the perforated cage 3, the bypass steam D then flows at high speed through holes (indicated by dashes in the FIGURE) in the turbine condenser 2. This gives rise to particularly high speed gradients specifically in the edge regions of the inflowing bypass steam D.

According to the invention, it is now the case that, in the inlet region, in the exemplary embodiment illustrated here immediately downstream of the perforated cage 3 of the bypass-steam introduction device 1, there is provided a ring-shaped nozzle 4, whose edge which points into the turbine condenser 2 is of serrated form, similarly to a crown. Such embodiments of non-uniform edges are known, for example from the field of aircraft engine construction, under the name “chevron nozzle”. By means of the edge which is made non-uniform by way of serrations Z, the high speed gradients that prevail in particular in the edge regions of the introduced bypass steam are locally broken up, and thus locally changed, over the circumference of the inflowing bypass steam. These speed gradients, which are now no longer uniform over the cross section in the edge regions, lead to more inhomogeneous mixing, and thus to an effective reduction of sound emissions. The sound emission limits that are demanded depending on the location of the installation can thus be adhered to even in the operating state in which the installation is operated merely at gas turbine minimum load.

Depending on the selected form and arrangement of the serrations or teeth, an edge is formed which may have elevations and/or indentations which are arranged so as to be distributed uniformly or else non-uniformly over the circumference of the edge. The serrations or teeth may in this case have any form, such as for example a triangular or trapezoidal form, and may also, if required, be curved in the direction of the axis A of the nozzle. Here, it is always important that highly uniform turbulent mixing of the bypass-steam jet with the surrounding steam in the turbine condenser 2, which can give rise to intense broad-band noise and thus high sound emissions, is prevented in a highly effective manner.

Even though the invention has, in the above exemplary embodiment, been described only in conjunction with a so-called “down-exhaust” turbine condenser with condenser tubes and condenser dome situated thereabove as transition chamber for receiving the exhaust steam from the adjacent steam turbine, it may in principle be used with any type of turbine condenser. Accordingly, the design according to the invention of the nozzle for the introduction of steam may also be used as a condenser connection in the case of axial turbine condensers, laterally arranged “single-side-exhaust” condensers or else bilaterally arranged “double-side-exhaust” condensers. 

1. A turbine condenser for a steam turbine, comprising: a region with condenser tubes for the liquefaction of exhaust steam from the steam turbine, having a chamber, formed by condenser walls, for receiving the exhaust steam, and having a bypass-steam introduction device for introducing bypass steam into said chamber of the turbine condenser, wherein the bypass-steam introduction device comprises a ring-shaped nozzle which extends into the turbine condenser, and the outlet end of which has a non-uniform edge.
 2. The turbine condenser as claimed in claim 1, wherein the edge is in the form of a serrated or toothed outlet edge.
 3. The turbine condenser as claimed in claim 2, wherein the edge has serrations or teeth distributed uniformly over the circumference.
 4. The turbine condenser as claimed in claim 3, wherein the serrations or teeth of the edge are at least partially inclined in the axial direction of the nozzle. 